Our long-term objectives on this project are to explore the molecular bases of membrane structure and function, with emphasis on the application of such information to problems of immunology, hematology, and lymphocyte biology. We propose to carry out the following specific studies: 1) to determine the rates of uptake of 3H-methochlorpromazine by intact human erythrocytes to test the bilayer couple hypothesis, which predicts a differential distribution of the compound in the two half-layers of the bilayer membrane, and a slow flip-rate between them; 2) to investigate possible differences in membrane mobility of the Rho(D) antigen in intact erythrocytes from Rh positive newborn compared to adult humans; 3) to study differences in the mobilities of components in the membranes of rabbit and human reticulocytes as compared to their mature erythrocyte counterparts; and (4) to study the ultrastructural localization, by immunoelectron microscopy, of mechanochemical proteins in lymphocytes that have undergone membrane capping reactions.